/*
  Copyright 2008 Google Inc.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
 */ 

package pat.solitaire;

public class LinkedStack {
    Link stack;

    public void push(Object v) {
	stack = new Link(v, stack);
    }
    public void pop()throws Exception {
	if(stack != null) stack = stack.next;
	    else throw new Exception("Pile vide");
    }
    public Object top()throws Exception {
	if(stack != null) return stack.value;
	    else throw new Exception("Pile vide");
    }
    public boolean isEmpty(){
	return stack == null;
    }
}

class Link {
    Object value;
    Link next;

    Link(Object _value, Link _next) {
	value = _value;
	next = _next;
    }
}
